Electrical relay.



B. H. SMITH.

ELECTRICAL RELAY.

APPHCATION FILED JULY 11.1914.

1,204,509. Patented Nov. 14, 1916.

UNITED STATES PATENT OFFICE.

BENJAMIN H. SMITH, OF TURTLE GREEK, PENNSYLVANIA, ASSIGNOR TO WESTING-HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYL-VANIA.

ELECTRICAL RELAY.

Specification of Letters Patent.

Patented Nov. 14, 1916.

To all whom it may concern: y

Be it known that I, BENJAMIN H. SMITH, a citizen of the United States,and a resident of Turtle Creek, in the county of Allegheny and State ofPennsylvania, have invented a new and useful. Improvement in ElectricalRelays, of which the following is a specification.

My invention relates to electrical protective devices and particularlyto relay mechanisms and systems that are employed for tripping circuitbreakers, or operating other devices, upon the occurrence ofpredetermined circuit conditions.

The object of my invention is to provide a simple and economical relaymechanism of the character indicated that may be operated by currentderived from the line or circuit in connection with which the circuitbreaker or other device is employed, thereby obviating the necessity ofemploying a separate source of power for supplying the operatingcurrent, and the contact members of which shall not be subjected toinjurious arcing, or to the possibility of welding or sticking together,or of becoming burned so that they will not conduct current.

Considerable diiiiculty has heretofore been experienced with relaymechanisms for circuit breakers and similar devices, that are employed'in connection with alternating current circuits, when it has beenattempted to derive "the current for tripping or operating the breakersfrom the said circuits. This dificulty has been due to the fact that thecurrent for operating the relay mechanism and'tripping the circuitbreakers has usually been derived from the main circuit by means of aseries transformer, the secondary circuit of which includes theoperating coil of the relay, the tripping coil of the circuit breakers,and the relay contact members which normally short circuit the lattercoil, but are separated to permit its energization upon the occurrenceof an overload or other predetermined circuit condition. Thereis usuallya sufiicient amount of current in this secondary circuit to cause arcingat the relay contact members, "and at times it may be sufiicient tocause them to weld or stick together, and the difliculty is renderedmore serious when there is slow separation of the contact members due tothe employment of a dash pot, or other retarding device, for introducinga time interval between the occurrence of an overload and the opening ofthe circuit breakers. Furthermore, arcing between the contact membersmay so burn and injure them as to prevent them from making goodelectrical contact when brought into engagement.

According to the present invention, I have provided a tripping devicethat is supplied with energy from the main circuit, but that does notrequire the interruption of a circuit carrying an appreciable current,thereby overcoming the hereinbefore mentioned difliculties.

In another application, Serial No. 850,331, filed of even date herewith,I have disclosed an electromagnetic tripping device for circuit breakersand similar apparatus that involves only the addition of a small corepart and two coils to the parts of present standard relay devices. Inthe present instance, I have provided a completely new structure for theelectromagnetic tripping device to accomplish the same results as areaccomplished by the device of the aforesaid ap plication.

The single figure of the accompanying drawing is a diagrammatic view ofa part of a system embodying my invention.

A typical system in connection with which the present invention may beemployed comprises an alternating current circuit 1 that is adapted tobe interrupted by means of a circuit breaker 2 and in series with oneconductor of which is the primary winding 3 of a current transformer 4,the circuit of the secondary winding 5 of which includes the circuit 1,or of any other desired abnormal circuit condition. This relay may bearranged to close the switch 8 instantaneously, or after a timeinterval, as desired.

The circuit breaker is adapted to be tripped by means of anelectromagnetic relay or tripping device that comprises a pivotallymounted armature 10 and two magnetizable core parts 11 and 12 that arearranged substantially in the form of a hollow rectangle with spaces orair gaps 13 and 14 between their opposing or abutting faces.

' of the armature 10 is then drawn to the The lower end of the armature10 extends into the air gap 14, but is not of suflicient width toentirely close or bridge the gap. In fact, the width of the air ga 14 isgreater than the combined widths o the armature 10 and air gap 13, sothat normally the air gap between the right side of the armature 10 andthe adjacent pole face of the core part 11 is greater than the width ofthe air gap 13. A spring 15 serves to normally maintain the lower end ofthe armature 10 in engagement with, or closely adjacent to, the pole"face of the core part 12.

The armature 10 is surrounded by a coil 16 that receives current fromthe secondary winding 5 of. the series transformer, the internaldiameter of-the coil being such as to permit of movement of the armaturebetween the opposing pole faces of the core parts 11 and 12. The part 12is surrounded by coil 17 v the circuit of which is normally open but isadapted to be closed or short circuited by the switch 8 of the relay 7.I

The core parts 11 and 12 provide a divided magnetic circuit .for fluxset up in the armature by the coil 16. Inasmuch as the spring 15maintains the lower end of the armature 10 closely adjacent to the lowerend of the core partzl2, the reater portion of the flux will traversethe livision of the magnetic circuit provided largely by the core part12, because the air gap 13 is shorter than the air gap 14, andthereluctance of the said division of the magnetic circuit is less thanthat of the other division. This condition will prevail'so long as theload upon the circuit 1 and the other electrical conditions thereof arenormal. However, upon the occurrence of an overload upon the circuit 1,orof some other abnormal condition, the relay 7 will close the switch 8and thereby establish a short circuit for the coil 17.

The short circuiting of the coil 17 causes the effective reluctance ofthe division of the magnetic circuit includin the core art 12,

to be very materially increased, thereby causing the greater portion ofthe flux produced by the current in the coil 16 to. traverse thedivision of the magnetic circuit provided by the core part 11. The lowerend right, and the tripping mechanism of the the flux traversing thearmature, one of able armature and two magnetic paths for the fluxtraversing the armature, one of which includes a substantially constantair gap and the other of which includes a variable air gap, a mainwinding surrounding the armature, and an auxiliary winding for themagnetic path that includes the constant air gap, the circuit of theauxiliary winding being controlled by the said relay.

3. An electromagnet comprising a magnetizable core having a movablearmature and a divided magnetic circuit presenting poles upon oppositesides of the armature, one of said divisions including an air gap, amain winding for the armature, and an auxiliary winding for the coredivision that does not include the air gap.

4. An electromagnet comprising a magnetizable core having a movablearmature and a divided magnetic circuit presenting poles upon oppositesides of the armature,

one of said divisions including an air gap, a normally energized windingfor the armature, and a normally denergized winding for the coredivision that does not include the air gap.

5. An electromagnet comprising a magnetizable core having two air gapsof unequal width, an armature extending into the wider air gap anddividing the core into two magnetic circuits one of which includes thenarrower air gap, a main winding for the armature, and an auxiliarywinding for the core division that includes the narrower air gap.

6. An electromagnet comprising a magnetizable core having two air gapsof unequal width, an armature extending -into the wider air gap anddividin the core into two magnetic circuits'one 0 which includes thenarrower air gap, anormally energized main winding surrounding thearmature, and a normally deenergized auxiliary winding for the coredivision that includes the relatively narrower air gap.

7 The combination with an electrical circuit and a relay, of anelectromagnet comprising a magnetizable core having a movablearmatureand two magnetic paths for the flux traversing the armature one of whichnormally has greater reluctance than the other, and a winding for thepath of lesser reluctance that is controlled by the relay for increasingthe effective reluctance of the path of normally lesser reluctance underpredetermined conditions.

8. An electromagnet comprising a magnetizable core having a movablearmature and two magnetic paths for the flux traversing the armature,one of which includes an air gap, a main Winding surrounding thearmature, and an auxiliary Winding :tor the path that does not includethe air gap.

9. An electromagnet comprising a magnetizable core having a movablearmature and two magnetic paths for the flux traversing the armature,one of which includes an air gap, a main winding for the armature, andan auxiliary Winding for the path that does not include the air gap.

10. An electromagnet comprising a magnetizable core having a movablearmature and two magnetic paths for the flux traversing the armature,one of which includes a substantially constant air gap irrespective ofthe movement of the armature, a main winding surroundin the armature,and an auxiliary Winding tor the path that does not include the air ga11. An electromagnet comprising a magnetizahle core having a movablearmature and two magnetic paths for the flux traversing the armature,one of which includes an air gap, a normally energized main Windingsurrounding the armature, and normally deenergized auxiliary windingsfor the magnetic path that does not include the air gap.

12. The combination With an electrical circuit and a relay, of anelectromagnet comprising a magnetizable core having a movable armatureand two magnetic paths for the flux traversing the armature one of whichnormally has greater reluctance than the other, a Winding for thearmature, and

a winding for the path of lesser reluctance that is adapted to heshort-circuited by the relay for increasing the efiective reluctance ofthe path of normally lesser reluctance under predetermined conditions.

13. An electromagnet comprising a mag netizable core having a movalolearmature and two magnetic paths for the flux that traverses thearmature, one of which includes a constant air gap and the other ofwhich includes a variable air gap, and a Winding for the magnetic paththat includes the constant air gap.

M. An electromagnet comprising a magnetizahle core having a movablearmature and two magnetic paths for the Hun that traverses the armature,one path of which normally includes an air gap, and means for increasingthe effective reluctance of the path that does not normally include theair gap. v

15. An electromagnet comprising a magnetizable core having a movablearmature and two magnetic paths for the flux traversing the armature,one of which includes an air gap, a normally energized main Windingsurrounding the armature, and an auxiliary Winding for the magnetic paththat does not include the air gap, said auxiliary Winding being adaptedto be short circuited under predetermined conditions.

in testimony whereof, I have hereunto subscribed my name this 80th dayof une,

BENJAMIN H. SMITH. Witnemes:

PAUL MAcGAr-ran,

B. Hines.

